At the end of September all eyes turned to Las Vegas, for the grand opening of a spectacular new entertainment attraction known simply as Sphere. The name gives nothing away; at more than 100m high and 150m wide, the Sphere could be a spaceship escaped from nearby Area 51; like an alien artifact, its outer skin radiates in technicolor, covered in a video display of enough brightness and resolution that it can visibly morph into an eyeball, a planet – and pretty much anything else round enough to make the illusion work. Yet that exterior, though remarkable, doesn’t hold a candle to the magic of its interior.

Half of the interior of the Sphere contains steep stadium seats accommodating almost 19,000 people, all pointing toward a stage. But that stage isn’t the star attraction at the Sphere. The other half of the interior acts as a single very high-resolution display. Stretching up a hundred meters behind the stage, and spanning hundred meters on both stage right and left, a vast array of LED ‘pixels’ stud the surface at 20 cm intervals, each capable of generating any of 256 million colours. While that might sound as though it could make the image look weirdly blocky and splotchy, the audience is more than a hundred meters from the wall, making those pixels appear closer together. This is the opposite end of the very same ‘retina’ effect that makes current-generation smartphones look so crisp; the pixels are closer together than the ability of our eyes to resolve them individually. It gives the impression of a ultra-ultra-ultra high resolution image – the equivalent of an array of 256 high-definition television screens.

The effect is beyond spectacular. When U2 mounted the stage for their inaugural concert – and the premiere of the Sphere – even they were gobsmacked by the overwhelming performance playing out just behind them. The illuminated surface continually transformed: at one moment being a hyper-realistic version of Las Vegas just on the other side of the Sphere, at another moment the desert landscapes of Joshua Tree, another looking like the inside of a gigantic concrete container, etc.

As I watched the first videos of that performance – posted just a few hours after the event concluded – I realised that we’d taken a step forward into a new kind of entertainment – with roots that stretch back more than thirty years. In the early 1990s, virtual reality had the same sort of buzz artificial intelligence does today, but very few people had actually been inside a VR environment. Rare, expensive and delicate, only researchers had regular access to the tech, and even the very best of those systems (which could run several million dollars), using state-of-the-art components, presented fuzzy views into their virtually generated landscapes.

Like an alien artifact, its outer skin radiates in technicolor.

Why? The ‘head-mounted displays’ that had become the recognisable hallmark of the VR experience used an individual display for each eye, but offered perhaps 300 pixels spread across 80 degrees of a ‘field of view’. A little armchair math will tell you that means each pixel had to cover nearly one third of a degree of the field of view, or 3.75 ‘pixels per degree’. When you consider that the full moon in the night sky only spans about half a degree, you can begin to see why that level of resolution might prove to be insufficient for – well, almost everything.

While better displays would have solved this problem, the technology for tiny high resolution displays lay two decades in the future. Until the smartphone took off, neither chip designers nor display manufacturers had enough market demand to invest billions of dollars in new processes that gave us today’s retina-class displays. But we already had technology for large high-resolution displays – data projectors. Buoyed by the new market for ‘home theaters’ using projection displays, in the 1990s, if you had the money, you could project a high-resolution image on any surface.

Putting us bodily into a virtual world transports our imaginations far more effectively than donning a ‘face-sucker’ display.

VR researcher Carolina Cruz-Niera and her colleagues at the University of Illinois, Chicago realised that they could use data projectors to turn VR ‘inside out’. Rather than projecting generated images within a head-mounted display, why not use data projectors to project the imagery onto the walls? No need for a bulky, heavy, low-resolution headset – and as an added bonus, you could bring multiple people into the virtual world together simultaneously. This ‘CAVE Virtual Environment’ created quite a stir in VR circles, upending design tenets, and revolutionising the scope for virtual reality. Now that any sufficiently darkened room could be repurposed as a virtual environment, people got very creative, very quickly. The CAVE worked both as a technology and as a fundamental statement of design – that VR could be flipped around and opened up, revealing a new way of thinking about space.

Across the middle of the 1990s a range of VR works either used the CAVE or adapted bits of it in some spectacular walk-around and walk-through VR works. It’s a technology that remains vital today; a recent work, Parragirls, uses walk-through immersion to document the true and horrifying tales of abuse at the Parramatta Girl’s Reformatory. Where headset VR often struggles to create a sense of place – people tend to remain stationary, for reasons of safety – CAVE-based VR gives you a whole-body sense of ‘immersion’.

It’s that same sense of immersion experienced by the audience at the Sphere. Putting us bodily into a virtual world transports our imaginations far more effectively than donning a ‘face-sucker’ display. And a CAVE wouldn’t be ideal for every possible application of VR, in most cases we prefer the virtual world to spread itself out around us, rather than being forced to squeeze ourselves into it.

Cities will soon vie to build their own Spheres.

Now that we’ve got a CAVE capable of handling nearly twenty thousand simultaneous ‘immersants’ – and one that appears to be hugely successful – we can expect the tech to spread everywhere. Cities will soon vie to build their own Spheres; it’s easy to imagine them popping up in Shanghai, Singapore, and Dubai. Every metropolis with pretensions to ‘world city’ status will be looking to build their own Sphere – the better to attract top-of-the-line entertainers. And while there will be a mad dash to build Spheres, it’s also easy to see another line of development that will bring the Sphere home.

Latest generation ‘gaming’ displays for PCs have grown wider and wider, so much so they now curve back toward the user at the edges, suggesting the start of a Sphere-like wraparound. Make them four times taller and twice as wide, and you’d have something I’m calling the ‘HomeSphere’ – the must-have consumer display of the early 2030s. The CAVE will come home as a new high-tech toy, a nod back thirty thousand years, to those first light shows playing out on cave walls.